<link rel="import" href="../polymer/polymer.html">
<link rel="import" href="../paper-icon-button/paper-icon-button.html">
<link rel="import" href="../iron-icons/iron-icons.html">
<link rel="import" href="../paper-toggle-button/paper-toggle-button.html">
<link rel="import" href="../paper-input/paper-input.html">

<!--
`tf-regex-group` provides an input component for a group of regular expressions.

Example:
  <tf-regex-group regexes="{{regexes}}"></tf-regex-group>

It contains a series of regular expression input fields. From this, it computes
`regexes', an array in which every element is either a string representing an
active, valid, nonempty regular expression, or the value `null`

Public Properties:
`regexes` a readonly, notifying array of strings, where each string is an
  active, valid, nonempty regex

It maintains an invariant that the final regex should always be an empty string,
so the user can easily add more regular expressions. It does this by adding
a new empty regex when the final one is nonempty.

Pressing "enter" moves focus to the next regex (or just blurs if there are no
more regexes).
-->
<dom-module id="tf-regex-group">
  <template>
    <div class="regex-list">
      <template is="dom-repeat" items="{{rawRegexes}}">
        <div class="regex-line">
          <paper-checkbox
            class="active-button"
            checked="{{item.active}}"
            disabled="[[!item.valid]]"
          ></paper-checkbox>
          <paper-input
            id="text-input"
            class="regex-input"
            label="Regex filter"
            no-label-float
            bind-value="{{item.regex}}"
            invalid="[[!item.valid]]"
            on-keyup="moveFocus"
          ></paper-input>
          <paper-icon-button
            icon="close"
            class="delete-button"
            aria-label="Delete Regex"
            tabindex="0"
            on-tap="deleteRegex"
          ></paper-icon-button>
        </div>
        <style>
          .regex-input {
            width: 230px;
            display: inline-block;
            margin-left: -3px;
          }

          paper-checkbox {
            --paper-checkbox-checked-color: var(--tb-ui-dark-accent);
            --paper-checkbox-unchecked-color: var(--tb-ui-dark-accent);
          }

          .delete-button {
            color: var(--paper-grey-700);
            width: 40px;
            height: 40px;
            margin-right: -10px;
          }

          .regex-list {
            margin-bottom: 10px;
          }
          
          paper-input {
            --paper-input-container-focus-color: var(--tb-orange-strong);
            --paper-input-container-input: {
              font-size: 14px;
            };
            --paper-input-container-label: {
              font-size: 14px;
            };
          }
        </style>
      </template>
    </div>
  </template>
  <script>
    Polymer({
      is: "tf-regex-group",
      properties: {
        rawRegexes: {
          type: Array,
          value: function() {
            return [{regex: "", active: true, valid: true}];
          }
        },
        regexes: {type: Array, computed: "usableRegexes(rawRegexes.*)", notify: true},
      },
      observers: [
        "addNewRegexIfNeeded(rawRegexes.*)",
        "checkValidity(rawRegexes.*)",
      ],
      checkValidity: function(x) {
        var match = x.path.match(/rawRegexes\.(\d+)\.regex/);
        if (match) {
          var idx = match[1];
          this.set("rawRegexes." + idx + ".valid", this.isValid(x.value));
        }
      },
      isValid: function(s) {
        try {
          new RegExp(s);
          return true;
        } catch (e) {
          return false;
        }
      },
      usableRegexes: function(regexes) {
        var isValid = this.isValid;
        return regexes.base.filter(function (r) {
          // Checking validity here (rather than using the data property)
          // is necessary because otherwise we might send invalid regexes due
          // to the fact that this function can call before the observer does
          return r.regex !== "" && r.active && isValid(r.regex);
        }).map(function(r) {
          return r.regex;
        });
      },
      addNewRegexIfNeeded: function() {
        var last = this.rawRegexes[this.rawRegexes.length - 1];
        if (last.regex !== "") {
          this.push("rawRegexes", {regex: "", active: true, valid: true});
        }
      },
      deleteRegex: function(e) {
        if (this.rawRegexes.length > 1) {
          this.splice("rawRegexes", e.model.index, 1);
        }
      },
      moveFocus: function(e) {
        if (e.keyCode === 13) {
          var idx = e.model.index;
          var inputs = Polymer.dom(this.root).querySelectorAll(".regex-input");
          if (idx < this.rawRegexes.length - 1) {
            inputs[idx+1].$.input.focus();
          } else {
            document.activeElement.blur();
          }
        }
      }
    });
  </script>
</dom-module>
